There is a continuing need in various research and industrial arts for ethylenically unsaturated polymerizable monomers which can be polymerized into useful polymers. For example, in the photographic arts, there is a need for layers in photographic elements which neutralize highly alkaline materials or which dissolve after a defined time to allow development or other chemical reactions. Such layers are often called "neutralizing" and "timing" layers. In other materials, there is a need for hardenable layers to immobilize various addenda or reactants. It is known in these arts to use polymers having reactive carboxy groups appended thereto. Typical polymers are those prepared from acrylic and methacrylic acids.
Moreover, there is also a continuing need in medical practice and research, and in analytical and diagnostic procedures for rapid and accurate determinations of chemical and biological substances which are present in various fluids, such as biological fluids. For example, the presence of drugs, narcotics, hormones, steroids, polypeptides, metabolites, toxins, viruses, microorganisms or nucleic acids in human or animal body fluids or tissues must be determined rapidly and accurately for effective research, diagnosis or treatment.
In approximately the last twenty years, a wide variety of analytical methods have been developed to detect the substances noted above. Generally, the state of the art has advanced to such a degree that analytical and diagnostic methods have become highly reliable, and suitable for automation or for use with test kits which can be readily used in doctors' offices or at home. Most of such methods rely on what are known in the art as "specific binding" reactions in which an unknown substance to be detected (known as a "ligand") reacts specifically and preferentially with a corresponding "receptor" molecule. Most well known specific binding reactions occur between immunoreactants, such as antibodies and antigens (foreign substances which produce immunological responses).
Methods in the art using the specific binding reactions generally require that one or more or both of the reactants be immobilized on a solid substrate of some type, so that unreacted (and generally water-soluble) materials can then be separated from the water-insoluble reaction product (often called a "complex"). In addition, such immobilized reactants can be used in affinity chromatography to remove a desired biologically active material from a mixture of such materials.
Biologically active substances have thus been immobilized to advantage on particulate substrates such as polymeric particles, animal and human erythrocytes, bacterial cells and other materials known in the art. In some cases, the particulate substrates are fashioned or chemically treated to provide reactive groups on their outer surfaces for appropriate reaction with the biological substance. If the particulate substrate is a polymeric material, it often can be prepared from monomers having the appropriate reactive groups.
For example, carboxylated latex particles have been used to prepare diagnostic reagents, as noted in U.S. Pat. No. 4,181,636 (issued Jan. 1, 1980 to Fischer). The described particles are prepared using a carboxyl-containing monomer such as acrylic acid, methacrylic acid, itaconic acid, aconitic acid, fumaric acid or maleic acid. Similar particles are described in U.S. Pat. No. 3,857,931 (issued Dec. 31, 1974 to Hager), U.S. Pat. No. 4,138,383 (issued Feb. 6, 1979 to Rembaum et al) and U.S. Pat. No. 4,264,766 (issued Apr. 28, 1981 to Fischer).
Two known monomers, 3-acrylamido-3-methylbutanoic acid and 2-acrylamido-2-hydroxyacetic acid, have been polymerized to form polymers. These monomers are generally water-soluble and are difficult to copolymerize with oleophilic monomers and are not readily polymerized to form monodisperse particles. For example, U.S. Pat. No. 4,728,436 (issued Mar. 1, 1988, to Kneller et al) describes water-soluble polymers for use as scale inhibitors in industrial water.
U.S. Pat. No. 4,634,651 (issued Jan. 6, 1987 to Okawara et al) describes crosslinked resins useful in liquid developers for electrostatic photography. The resins have electric charge due to the presence of carboxy groups within the crosslinked resin matrix. The polymers used to prepare the resins are prepared in organic solvents.
In U.S. Pat. No. 4,574,130 (issued Mar. 4, 1986, to Potter et al), there are disclosed ethylenically unsaturated polymerizable monomers which are precursors to polymers useful as surfactants in medical or surgical adhesives. These polymers are highly water-soluble and not suitable for forming small particles. Moreover, such polymers generally have low glass transition temperatures.
Another advance in the art relates to the use of specific compounds to attach biological materials to particulate substrates having reactive carboxy groups. Generally, water-soluble carbodiimides have been used, as described in the references noted above. More recently, however, carbamoylonium compounds have been used for this purpose with considerable advantages, as described in U.S. Ser. No. 373,304 (filed Jun. 29, 1989 by Sutton et al) as a CIP of U.S. Ser. No. 286,097 (filed Dec. 19, 1988) which is a CIP of U.S. Ser. No. 098,429 (filed Sep. 18, 1987).
The modification of protein adsorption on polymeric surfaces has been a common goal for many workers trying to apply polymer technology to in vivo and in vitro uses in biotechnology. Undesirable protein absorption has been a continual problem. For example, nonspecific adsorption is a major concern in the use of polymers for affinity chromatography for the purification of proteins.
The modification of polymer surfaces has taken many forms, including physical coatings, graft copolymerization, chemical treatments and plasma gas discharge treatment. The hydrophilic nature of the polymer surface has been the subject of considerable debate and research because an increase in hydrophilicity reduces adsorption of some proteins, but not others. As noted in the art cited above, the use of reactive side chains has also received considerable attention in the art.
There is a need in the art to find new polymerizable monomers and water-insoluble polymers prepared therefrom which show improvement over the standard carboxy-containing polymers, especially in copolymerization efficiency and in the attachment of biological materials for use in research and various analytical and diagnostic procedures.